Heat sinks of the type considered herein are typically made of a metal, such as aluminum. Each of one or more transistors may be mounted on the heat sink by means of a spring clip which holds the transistor snugly against the heat sink. A typical arrangement is shown in FIG. 1.
The illustrated heat sink assembly includes an aluminum heat sink 10, a transistor 12, and a spring clip 14 that holds the transistor 12 against one wall of the heat sink 10. One end 16 of the spring clip is curved upwardly to form a grip which permits the clip to be opened to insert the transistor between the spring clip and the heat sink. The other end (not shown) of the spring clip 14 passes through an aperture 18 in the heat sink. Additional apertures 20, 22 are included to receive other spring clips so that a plurality of transistors may be mounted on the same heat sink 10.
The heat sink 10, along with the transistors and spring clips mounted thereon, are usually mounted on a printed circuit board 24. As shown, the board 24 has holes 26 through which the leads of the transistor 12 are to be inserted. Another hole 28 permits a screw 30 to pass through the board 24 and into the heat sink 10 for securely holding the heat sink to the board 24.
Although the heat sink assembly of FIG. 1 and others like it work reasonably well, they do have certain drawbacks. For example, it is desirable to more easily mate the spring clips to the heat sink. It is also desirable to be able to more densely mount a number of transistors on their common heat sink so that less space is required for heat sinking a given number of transistors. In addition, it is desirable to be able to mount a heat sink assembly on a printed circuit board (or on a different type of carrier) without the use of screws, bolts or the like. Factory assembly would be more efficient without the use of such extra fasteners.
Another drawback of conventional heat sink assemblies is that they do not adequately protect the leads of the mounted transistors during handling. With the arrangement of FIG. 1, for example, the leads of the transistor may become inadvertently bent, or otherwise misaligned with the holes 26, prior to fastening the heat sink assembly to the board 24. As more transistors are added to the heat sink 10, this problem becomes more acute.